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Scientist at University of Bath discovers how to make the perfect cup of coffee

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A chemist from the University of Bath has teamed up with the owner of an award-winning city centre cafe business to find out how to make the perfect cup of coffee.

PhD student Christopher Hendon and his friend Maxwell Colonna-Dashwood, from Colonna and Small’s, are now preparing to share their findings at the World Barista Championships in Italy this weekend.

They have discovered that the variety in the taste of different drinks comes down to the water.

Mr Hendon, who carried out the project in his spare time, said: “Coffee beans contain hundreds of chemicals; the precise composition depends on the type of bean and how it is roasted.

“The flavour of the resulting coffee is determined by how much of these chemicals are extracted by the water, which is influenced by roast profile, grind, temperature, pressure and brew time.

“We’ve found that the water composition is key to the proportions of sugars, starches, bases and acids extracted from a particular roast.”

Their study has now been published in the Journal of Agricultural Food Chemistry and includes information about how to match the best coffee bean to the type of water you have to hand.

Mr Colonna-Dashwood said: “For the championships we test the local water and then select the roast that is most suitable for that particular water.

“For example you could use a heavy roast with a soft water as it doesn’t extract very much, but with hard water it would extract too much and give a bitter taste, so it would be better to use a lighter roast.

“Traditionally the coffee-making industry is most concerned about using water that doesn’t scale up their machines.

“But we argue that more value should be placed on the flavour of the coffee and want to use chemistry to help people make the best coffee they can with the water they have available.”

The pair are now planning to share their knowledge on the science behind making the perfect coffee in a book.